Power generation from waterways is well-known and commonly practiced in coastal waters and rivers. A well-known application is in dams with built-in turbines driving generators for the production of electric power. Most navigable waterways have a controlled water level to facilitate shipping by maintaining minimum depths through the placement of dams in the waterway. Shipping is made possible through the location of locks adjacent to the dams.
The Mississippi River is an example of such a waterway with a controlled water level and a system of dams with locks. The water-level drop at most Mississippi River dams is 20 feet or less. One such dam and lock has a drop of 38 feet and has a hydroelectric power plant taking power from the waterway. The 38 feet of static head provides an opportunity to produce power efficiently since the head is substantially greater than the other dams in this waterway. The static head in most other dams is typically not sufficient to provide a satisfactory return-on-investment for a conventional hydroelectric power plant in conjunction with these dams.
The placement of dams also increases waterway draft for shipping and reduces and evens out the speed of the water flow, a benefit for the waterway shipping industry. Low-static-head systems have traditionally not attracted interest because the cost of building the conventional equipment to generate this power has been very high in relation to the benefit of the power produced. The present invention reduces the cost of the power-generating equipment to such a low level that power will now be able to be efficiently and cost-effectively produced using existing dams with low static heads.
Traditional generating systems consist of a turbine placed on a base, and the turbine is connected to a generator via a shaft and a coupling placed on that same base. The present inventive system provides for installation that is greatly simplified and reduces cost. This invention allows efficient, low-cost power generation for low-static-head applications that are not possible with conventional systems.
Cost reduction is accomplished by integrating the turbine and the electric power generator in one compact unit including non-metallic compounds to keep both cost and weight low. It is modular in design, allowing combinations of components to match with the power requirements of given applications without requiring custom designs. The inventive device fits in-line with water ducts for easy installation and maintenance. It is submersible and can be suspended under water in ways that are not possible or practical with a separate turbine and generator.
Most conventional hydroelectric power generation systems do not have the capability of reversing the operation and turning the power generation system into a pumping system by applying an electric current to the generator. The present invention allows the electric generator to become an electric motor, reversing its function by providing power to it. The axial flow turbine functions equally well as a pump so that the inventive system can be used to store energy by applying electric power to the unit and pumping water from a first reservoir to a higher-elevation second reservoir, effectively storing electrical energy by increasing the elevation of the stored water. When electronic commutation is reversed once again, it turns the power system back into a generator and so can recover the stored energy. Therefore, unlike most conventional hydroelectric power generators, the present invention can be used as an energy storage and recovery system. Because of the high efficiency of the axial flow design, both turbine and pumping functions provide the most efficient method of high-MWhr (megawatt-hour) energy storage and recovery.
The identical hardware that is the subject of this invention constitutes an electrically-powered pump for multiple industrial and marine applications such as industrial water pumps, pipeline pumps and marine propulsion systems. Conventional pumping systems consist of a separate pump and motor, requiring more complicated installation than the inventive integrated pump and motor. The integrated motor/pump configuration allows in-line installation in a pipeline for fluid transportation of all kinds, such as natural gas, oil, water and any fluid produced in industry that needs to be transferred. The high power density, non-corrosivity, and low weight of the integrated units allow in-line installation with both external dimensions and total weight five times less than the equivalent conventional pump and motor combination, all while making a pump house unnecessary.
In the prior art, a combined turbine/pump called the “Straflo” turbine (1) requires a foundation structure for support, (2) is produced entirely of metal components, (3) relies on mechanical seals to separate water from the electrical components, and (4) uses wicket gates to control flow. All four of these problematic considerations are eliminated by the present invention. The Straflo turbine does not have power-density obtained by the subject invention. Further, its cost is higher rather than lower than a conventional separate turbine and generator system.
Another prior art system is called the “Turbinator” which is an all-metal configuration that has metallic separation between water and the stator which increases weight lowers the power generation efficiency. The system also requires an oil bath with a separate cooling system to cool the stator. Therefore, its efficiency is substantially reduced and its weight is significantly higher.